How does it work?

This medicine contains the active ingredient efavirenz, which is a type of medicine called a non-nucleoside reverse transcriptase inhibitor. It is used in the treatment of HIV (human immunodeficiency virus) infection. AIDS (acquired immune deficiency syndrome) is caused by infection with HIV. This virus invades cells of the immune system, particularly the white blood cells known as CD4 T-helper lymphocytes. These cells normally work to activate other cells in the immune system to fight infection. Since HIV kills CD4 T-helper cells, over time the body becomes less able to fight the virus or subsequent infections. Once the virus is inside the CD4 T-cell it multiplies. Part of the process of viral multiplication involves the conversion of the virus genetic material, RNA, into DNA. This is achieved by a compound essential to the virus, called reverse transcriptase. Reverse transcriptase is a compound known as an enzyme. Efavirenz works by blocking the action of this enzyme, thereby interfering with the conversion of viral RNA into DNA. This stops the virus from multiplying. There is no cure for HIV, but efavirenz is one of a number of medications that lowers the amount of virus in the body (viral load) and slows the progression of the disease from HIV to AIDS. Efavirenz is used in combination with other anti-HIV drugs that attack the HIV virus in different ways. This minimises the virus's ability to replicate and multiply, and helps prevent it becoming resistant to treatment.

What is it used for?

HIV infection

Warning!

A rash is one of the most common side effects of this medicine. If the rash is mild to moderate your doctor may decide that the medicine can be continued, in which case the rash will usually resolve with continued treatment. However, sometimes a more severe rash can occur, in which case the medicine may need to be stopped. Consult your doctor immediately if you experience a rash while taking this medicine.

The HIV virus is very good at becoming resistant to anti-HIV medicines. For this reason it is very important that you carefully follow your doctor's instructions for taking your anti-HIV medicines, in order to maintain effective levels of the medicines in your blood. If the blood levels drop, the virus will be given more chance to replicate and develop resistance to the drugs. Skipping even a few doses increases the risk of treatment failure, so you should try to ensure that you take all your doses at the correct time, and that you visit your doctor for repeat prescriptions before you run out.

People with liver diseases should have their liver function monitored regularly while taking this medicine.

The manufacturer of this medicine has not studied its safety and effectiveness in children who are below three years of age, or who weigh less than 13kg.

This medicine may cause an increase in your blood cholesterol levels, and your doctor may want to monitor your cholesterol levels while you are taking this medicine.

Treatment of HIV infection with anti-HIV medicines such as this one does not reduce the risk of transmitting the virus to other people through sexual contact or blood contamination. You should continue to use condoms to prevent transmitting the virus to your sexual partner.

This medicine can sometimes cause side effects such as severe depression, delusions and psychosis, and some people have had thoughts of suicide or actually committed suicide. These problems are more likely to occur in people who have a history of mental illness. You should contact your doctor immediately if you think you are experiencing any of these psychiatric side effects, so that your doctor can decide if it is appropriate for you to continue to take the medicine.

You may experience side effects such as dizziness, insomnia, sleepiness, difficulty concentrating and unusual dreams while taking this medicine. These side effects tend to resolve after the first two to four weeks of treatment and may be improved if you take your dose at bedtime. If you experience these side effects it does not mean you are more likely to experience the rarer psychiatric side effects of this medicine, such as severe depression.

This medicine may cause dizziness, sleepiness and reduced concentration. If affected you should avoid potentially hazardous activities such as driving or operating machinary.

Use with caution in

Elderly people

History of depression

History of fits (seizures), eg epilepsy

History of hepatitis B or C

History of mental illness or substance abuse

Liver disease

Severely decreased kidney function

Not to be used in

Severely decreased liver function

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy. If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and Breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

The safety of this medicine for use during pregnancy has not been established. It is not recommended for use in pregnancy unless considered essential by your doctor. Seek medical advice from your doctor.

It is recommended that women infected with the HIV virus must not breastfeed their infants under any circumstances, in order to avoid transmission of the virus to the baby. Seek medical advice from your doctor.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

Headache

Blurred vision

Difficulty in sleeping (insomnia)

Depression

Confusion

Fatigue

Loss of contact with reality (psychosis)

False perceptions of things that are not really there (hallucinations)

Dizziness

Increased blood cholesterol level

Severe blistering skin reaction affecting the tissues of the eyes, mouth, throat and genitals.(Stevens-Johnson Syndrome)

Mental disorder characterised by irrationally held beliefs (paranoia)

Problems with coordination

Concentration difficulties

Sleepiness (somnolence)

Abnormal dreams

Liver disorders

Anxiety

Disturbances of the gut such as nausea, vomiting, diarrhoea or abdominal pain

Rash

The side effects listed above may not include all of the side effects reported by the drug's manufacturer. For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

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